Integral skin polyurethane foams are well known in the art. See, e.g., U.S. Pat. Nos. 3,523,918, 3,726,952, 3,836,487, 3,925,527, 4,020,001, 4,024,090, and 4,065,410. In general, such foams are prepared by reacting isocyanates with polyols in the presence of an organic blowing agent. Although the use of water as the only blowing agent to produce an integral skin polyurethane foam has been suggested (see, e.g., the above noted U.S. Patents), in all commercial applications of which Applicants are aware, the blowing agent is a chlorofluorocarbon such as monofluorotrichloromethane.
An isocyanate having an isocyanate group content of about 19% by weight and prepared by reacting (i) methylenebis(phenyl isocyanate), (ii) a carbodiimide group modified methylenebis(phenyl isocyanate) having an isocyanate group content of about 29% by weight and (iii) a 2000 molecular weight polyester diol is commercially available. In addition, blends of such isocyanates with urethane group containing isocyanates are also known (see, e.g., U.S. Pat. No. 4,986,929).
Systems are commercially available which are used in the production of polyurethane shoe soles. In general, these systems comprise a polyether diol, a polyether triol, a chain extender (such as 1,4-butane diol or ethylene glycol), an organic blowing agent, catalyst and surfactant. The use of so-called filled polyols in such systems is described in U.S. Pat. Nos. 4,448,903 and 4,477,602.